At business networking events I meet a lot of people who seem totally unprepared for the "So what do you do" question. Why not practise a short, helpful introduction for yourself. You will know when you have got it right when the person you are talking to says: 'How do you do that then?' There are only a few simple ingredients to a good introduction.
Something like "We help [target market] to [benefit]. For example, 'We help consultants double the value of their sales'. The trick is to make it interesting. So instead of telling people that you are an HR consultant, you might say: 'We help hotels retain their key staff.'